It is necessary to consider the relationship between International Law and Municipal Law in order to comprehend the relationship between the two. The issue of the relationship between international and municipal law rules is one of the most contentious issues in legal theory, and determining their relationship has now taken on practical significance. While international law is applicable to state relations and other international law topics, national or state law, also known as municipal law, is applied within a state to the persons and corporate bodies that bear rights and obligations under it.
Initially, the relation between the two laws was purely theoretical, i.e., if the Law of Nations and Municipal Law are parts of a single legal order or two separate legal systems. The most important issue before an international tribunal is whether international law takes precedence over municipal law or the other way around. The relationship between the two systems has gained prominence in contemporary international law, in part because so much of it is concerned with the actions of persons who fall under the authority of municipal courts. As a result, a growing portion of International Law is applied in municipal courts.
International law is also known as public international law and law of nations. It is a collection of laws, norms, and principles that are widely accepted in international relations, and it provides normative guidelines and a common conceptual structure to direct states in a variety of areas, including war, diplomacy, trade, and human rights. International law refers to a collection of laws that are widely recognized and acknowledged as binding in international relations. Many national legal systems accept international tradition, treaties, and general principles of law as origins of international law.
“Law of nation or international law is the name for the body of customary and convention rules which are considered legally binding by civilized states in their relation with each other, within a community which by common consent of this community shall be enforced by external power.” – Oppenheim
“That body of law which is composed for its greater part of its principles and rules of conduct which states feel themselves bound to observe, and therefore, do commonly observe in their relations with each other.” – G Starke
“The legal system governing the relationship between nations; more modernly the law of International relations; embracing not only nations but also such participants as International organizations and individuals.” – Black Law’s Dictionary
The Black Law’s Dictionary defined International Law as “the ordinances and other laws applicable within a city, town or other local Government entity”
In contrast to international law, municipal law is a sovereign state’s national, domestic, or internal law. Municipal law encompasses not only national law but also federal, provincial, tribal, municipal, and local law. It refers to the laws that regulate a specific city or nation, as well as the political bodies that govern certain cities or countries. As a result, municipal law refers to legislation enacted by a state’s legislature or law-making body that is only applicable to that state.
Relationship between International Law and Municipal law:
International law, in theory, exists only at the international level, not within domestic legal frameworks, which is consistent with positivism’s recognition of international and municipal law as separate and autonomous systems. No municipal rule can be used as an excuse for violating international law, according to a concept accepted both in International case laws and treaties. International law’s position in municipal law is more complicated, and it is determined by a country’s domestic legislation.
It’s critical to comprehend how international law concepts are incorporated into domestic law, as well as what happens when the laws clash. The two key theories that describe the relationship between international and municipal law are monism and dualism.
1. Monistic Theory: According to this theory, the domestic civil order is the only legal structure that exists. The proponents of this theory deny that international law is a separate and self-contained body of law. Kelson, an Austrian jurist, founded the monistic theory. Monists believe that both municipal and international law are members of a single universal legal framework that serves the interests of the human race in some way. As a result, the law of nations is indistinguishable from state internal or municipal law, and it is only relevant as part of the universal legal order. As a result, they are both genus-law organisms. Monistic theorists refuted Dualists’ claims that the two structures differed in terms of origins, substance, concepts, and subject matter.
2. Dualistic theory: The law of nations and the municipal laws of the various states, according to Dualistic theory, are two different, distinct, and self-contained legal structures. International Law does not form part of a state’s domestic law since it is a separate framework. Since they have no common grounds or subjects of application, such a view eliminates any debate over which form of law is superior to the other. Each is supreme in its own domain. The dualists argue that since international law can only address States and not persons, States are free to govern their internal affairs as they see fit and that international law has little or no influence over municipal law.
Triepel, a well-known German scholar, proposed this idea in 1899. Later on, Italian jurists Anzilotti and Starke adopted the idea. The two systems of law, according to the writers, differ in terms of sources, subjects, law substance, principles, and subject-matter dynamicism.
3. Specific Adoption Theory: It is based on the dualist philosophy. According to this principle, no laws of international law can claim to be enforced by municipal courts on their own force unless they are transformed and implemented directly by municipal courts and systems. Only if they are expressly adopted, international law laws become part of national law.
4. Transformation Theory: The laws of international law are transformed, according to proponents of this theory, for the application of international law in the field of municipal law. When international law becomes more widely accepted, it undergoes changes. It cannot be extended to local law until it is converted. States use a special “transformational” device to integrate treaties and norms into their municipal rules.
5. Delegation Theory: This theory states that the rules of international law known as “Constitutional rules of international/treaties” delegate a right to each state constitution, allowing each state to decide or determine for itself how and when the provisions of an international treaty or convention come into force, and how they are implemented or embodied in statutes.
6. Consent Theory: John Locke defined the development of this principle and coined the term “everyone is equal” from it. There were some issues with this, including the fact that treaties and customs were not the only origins of international law. In this principle, any party to a contractual arrangement will recognize all provisions of the international legal framework. The basis of International Law, according to Article 38(1) of the Tribunal Statutes, is “General Principles of Law Accepted by Many Civilized Countries.” It assists judges in developing international legal material. This demonstrates that for International Law to work, agreement is not always needed. When it comes to treaties, the consent principle isn’t entirely applicable. Although having an agreement with any other country is relevant, having the consent of a third country is not. So no third party will intervene in any of the States’ affairs.
Differences between International Law and Municipal Law:
The origins of law, its topics, and subject matter are thought to be the key differences between foreign and municipal law.
1. International law is primarily concerned with state relations, although it is not exclusively so. Municipal legislation regulates the interactions of individuals within the state as well as between individuals and the state.
2. International law governs relations between members of the States family of nations. Municipal law, on the other hand, governs the relationships between individuals who are subject to the jurisdiction of a particular state, as well as the relationships that exist between this state and the individuals who are subject to it.
3. The law of the nation is a law that governs the relationship between sovereign states rather than above them. Municipal law, on the other hand, is the law of the sovereign over persons as subjects.
4. International law is derived from states’ common will, its objects are the states themselves, and its subject matter is international affairs. Domestic law is derived from the sovereign’s or state’s will, its subjects are persons within the state, and its subject matter is the relationships between individuals and government.
Position in India:
The Rules of International Law are only referred to in the most general terms in the Indian Constitution, implying that the drafters of the Indian Constitution were highly ambiguous in describing the status of International Law in the municipal sphere. The relationship between foreign and municipal law is not well described in our Constitution. India has not deviated from the common law status, according to a composite reading of Articles 51(c) 253, and 372. As a result, India will continue to treat customary international law as part of the law of the land, as long as it does not conflict with current constitutional provisions or the national charter.
In several cases, including Vishakha vs. State of Rajasthan, Randhir vs. Union of India, and Unnikrishnan vs. State of Karnataka, the Supreme Court has held that India’s domestic rules, including the constitution, are not to be read as violating international law. In the event of any misunderstanding, an attempt should be made to read domestic law as being in accordance with international law. Nonetheless, the constitution remains the supreme rule of the nation, and in the event of a direct dispute, the constitution will take precedence. In the case of BehramKhurshid v. State of Bombay, it was determined that Privy Council rulings were not entirely binding on Indian courts; instead, the court would examine the case’s rules and evidence to determine whether or not they were valid. The Indian legal system would recognize international laws as long as they did not supersede local laws and respected and adhered to international rules and norms.
It is commonly seen that National and International legal structures operate in their own jurisdictions and they did not pose any threat of retribution and retaliation with each other. Both structures are necessary and often helpful, and they also interact with one another in a current context in relation to a variety of issues. Since Monist theorists claim that International Law can fix any problems that have arisen within any State, International Law is thought to be higher than Municipal Law. International Law was earlier considered as the law between nations, but the position does not hold true today. Now, it also embraces individuals. International Law gradually headed towards a human commonwealth encompassing individuals, states and other aggregates cutting across state boundaries.
It was also believed and argued by Kelsen that International law is such a law which applies to any aspect of human life. International Law, according to monistic theorists, is not covered by any law; rather, Municipal Laws are a part of International Law. Unless the nation-state agrees to do so, it is not required to follow international law. Despite the fact that both ideas have a position in international law, only a few countries in the world practice pure dualism or monism. When international law is in the favor, they obey it; when it is not, they do not. The doctrine’s central tenet is to keep all national and international laws in order. It eliminates the distinction between foreign and municipal law and establishes interdependence between the two for a more efficient judicial process.
 Malcolm Shaw, “International Law”, Encyclopaedia, Britannica
 Lassa Oppenheim, “International Law: a treatise”, Vol. 8, H. Lauterpacht ed., 8thedn, Peace, 1955
Mohd.AqibAslam, “International Law: Definition, Nature and Basis”, Legal Service India, available on http://www.legalserviceindia.com/legal/article-2167-international-law-definitions-nature-and-basis.html, retrieved on: April 13, 2021
 Black Laws Dictionary
 Alabama Claims Case
 Vienna Convention on the Law of Treaties, Article 27
United Nations, Statute of the International Court of Justice, Article 38(1),18 April 1946
 Constitution of India, Articles 51(c), 253 and 372.
 AIER 1997 SC 3011
 1982 AUR 879
 1993 AIR 2178
 AIR 1955 SC 123